1. Field of the Invention
The present invention relates to a fuel injection type two-cycle engine for motorcycles and a motorcycle loaded with this engine.
2. Description of the Relevant Art
In a reed valve type two-cycle engine, a thin-plate-shaped reed valve which opens as attracted towards the side of a crank chamber in accordance with a pressure difference between the inside and the outside of the crank chamber produced by a piston motion and closes due to its own resilient force when the pressure difference has been lowered, is disposed at a suction port portion provided at the crank chamber or a cylinder portion and communicated with an air intake passageway, so that air would be sucked into the engine when the reed valve opens. Fuel is fed into the sucked air within the air intake passageway, and an engine designed so as to perform this fuel feed by means of a fuel injection valve has been known, for instance, such an engine is disclosed in Laid-Open Japanese Patent Specification No. 58-98632.
In this engine, an amount of sucked air is detected on the basis of a magnitude of variation of an inner pressure within a crank chamber, and depending upon this detected value, an injection signal having a predetermined time width is output from a control device consisting of a digital computer or the like to a fuel injection valve. When the above-mentioned injection signal is input, the fuel injection valve opens only during the time width and injects an appropriate amount of fuel into the air intake passageway.
However, in the above-described fuel injection device in the prior art, since a jet port of the fuel injection port is directed towards the wall of the air intake passageway and the injected fuel is at first blown onto this wall, fuel would adhere onto the wall, hence mistification of fuel would be prevented, and waste of fuel was liable to occur.
In general, an engine for a motorcycle is desired to have a small width in view of its relation to a vehicle body, and also, as it is equipped by effectively utilizing a narrow space around a vehicle body frame, it is necessary to pay special attention to ease of maintenance and cooling of the engine and air intake.